The field of art to which this invention pertains is the cooling of fluidized particles. It particularly relates to the combustion of combustible material from a particulated solid such as fluidized catalyst which has been at least partially deactivated by the deposition thereon of a combustible material, such as coke and the cooling of such particles in a vessel that is separate and distinct from the vessel in which such combustion takes place. The present invention will be most useful in a process for regenerating coke-contaminated particles of fluidized cracking catalyst, but it should find use in any process in which combustible material is burned from solid, fluidizable particles.